• The Korean Journal of Physiology and Pharmacology
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• 제16권2호
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• pp.113-118
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• 2012

Ginsenosides are low molecular weight glycosides found in ginseng that exhibit neuroprotective effects through inhibition of $N$-methyl-D-aspartic acid (NMDA) receptor channel activity. Ginsenosides, like other natural compounds, are metabolized by gastric juices and intestinal microorganisms to produce ginsenoside metabolites. However, little is known about how ginsenoside metabolites regulate NMDA receptor channel activity. In the present study, we investigated the effects of ginsenoside metabolites, such as compound K (CK), protopanaxadiol (PPD), and protopanaxatriol (PPT), on oocytes that heterologously express the rat NMDA receptor. NMDA receptor-mediated ion current ($I_{NMDA}$) was measured using the 2-electrode voltage clamp technique. In oocytes injected with cRNAs encoding NMDA receptor subunits, PPT, but not CK or PPD, reversibly inhibited $I_{NMDA}$ in a concentration-dependent manner. The $IC_{50}$ for PPT on $I_{NMDA}$ was $48.1{\pm}4.6\;{\mu}M$, was non-competitive with NMDA, and was independent of the membrane holding potential. These results demonstrate the possibility that PPT interacts with the NMDA receptor, although not at the NMDA binding site, and that the inhibitory effects of PPT on $I_{NMDA}$ could be related to ginseng-mediated neuroprotection.

• Journal of Ginseng Research
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• 제43권2호
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• pp.261-271
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• 2019

Background: Protopanaxatriol (PPT) is an aglycone of ginsenosides, which has high medicinal values. Production of PPT from natural ginseng plants requires artificial deglycosylation procedures of ginsenosides via enzymatic or physicochemical treatments. Metabolic engineering could be an efficient technology for production of ginsenoside sapogenin. For PPT biosynthesis in Panax ginseng, damarenediol-II synthase (PgDDS) and two cytochrome P450 enzymes (CYP716A47 and CYP716A53v2) are essentially required. Methods: Transgenic tobacco co-overexpressing P. ginseng PgDDS, CYP716A47, and CYP716A53v2 was constructed via Agrobacterium-mediated transformation. Results: Expression of the three introduced genes in transgenic tobacco lines was confirmed by Reverse transcription-polymerase chain reaction (RT-PCR). Analysis of liquid chromatography showed three new peaks, dammarenediol-II (DD), protopanaxadiol (PPD), and PPT, in leaves of transgenic tobacco. Transgenic tobacco (line 6) contained $2.8{\mu}g/g$ dry weight (DW), $7.3{\mu}g/g$ DW, and $11.6{\mu}g/g$ DW of PPT, PPD, and DD in leaves, respectively. Production of PPT was achieved via cell suspension culture and was highly affected by auxin treatment. The content of PPT in cell suspension was increased 37.25-fold compared with that of leaves of the transgenic tobacco. Transgenic tobacco was not able to set seeds because of microspore degeneration in anthers. Transmission electron microscopy analysis revealed that cells of phloem tissue situated in the center of the anther showed an abnormally condensed nuclei and degenerated mitochondria. Conclusion: We successfully achieved the production of PPT in transgenic tobacco. The possible factors deriving male sterility in transgenic tobacco are discussed.

• Journal of Ginseng Research
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• 제35권2호
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• pp.191-199
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• 2011

The human ether-a-go-go-related gene (HERG) cardiac $K^+$ channels are one of the representative pharmacological targets for development of drugs against cardiovascular diseases such as arrhythmia. Panax ginseng has been known to exhibit cardioprotective effects. In a previous report we demonstrated that ginsenoside $Rg_3$ regulates HERG $K^+$ channels by decelerating deactivation. However, little is known about how ginsenoside metabolites regulate HERG $K^+$ channel activity. In the present study, we examined the effects of ginsenoside metabolites such as compound K (CK), protopanaxadiol (PPD), and protopanaxatriol (PPT) on HERG $K^+$ channel activity by expressing human a subunits in Xenopus oocytes. CK induced a large persistent deactivatingtail current ($I_{deactivating-tail}$) and significantly decelerated deactivating current decay in a concentration-dependent manner. The $EC_{50}$ for persistent $I_{deactivating-tail}$ was $16.6{\pm}1.3$ ${\mu}M$. In contrast to CK, PPT accelerated deactivating-tail current deactivation. PPD itself had no effects on deactivating-tail currents, whereas PPD inhibited ginsenoside $Rg_3$-induced persistent $I_{deactivating-tail}$ and accelerated HERG $K^+$ channel deactivation in a concentration-dependent manner. These results indicate that ginsenoside metabolites exhibit differential regulation on Ideactivating-tail of HERG $K^+$ channel.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2012년도 정기총회 및 춘계학술발표회
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• pp.20-20
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• 2012

Isoprenoids represent the most diverse group of metabolites, which are functionally and structurally identified in plant organism to date. Ginsenosides, glycosylated triterpenes, are considered to be the major pharmaceutically active ingredient of ginseng. Its backbones, categorized as protopanaxadiol (PPD), protopanaxatriol (PPT), and oleanane saponin, are synthesized via the isoprenoid pathway by cyclization of 2,3-oxidosqualene mediated with dammarenediol synthase or beta-amyrin synthase. The rate-limiting 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), which is the first committed step enzyme catalyzes the cytoplasmic mevalonate (MVA) pathway for isoprenoid biosynthesis. DXP reductoisomerese (DXR), yields 2-C-methyl-D-erythritol 4-phosphate (MEP), is partly involved in isoprenoid biosynthesis via plastid. Squalene synthase and squalene epoxidase are involved right before the cyclization step. The triterpene backbone then undergoes various modifications, such as oxidation, substitution, and glycosylation. Here we will discuss general biosynthesis pathway for the production of ginsenoside and its modification based on their subcellular biological functions.

• Journal of Ginseng Research
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• 제38권4호
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• pp.270-277
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• 2014

Background: The effect of methyl jasmonate (MJ) on ginsenoside production in different organs of ginseng (Panax ginseng Meyer) was evaluated after the whole plant was dipped in an MJ-containing solution. MJ can induce the production of antioxidant defense genes and secondary metabolites in plants. In ginseng, MJ treatment in adventitious root resulted in the increase of dammarenediol synthase expression but a decrease of cycloartenol synthase expression, thereby enhancing ginsenoside biosynthesis. Although a previous study focused on the application of MJ to affect ginsenoside production in adventitious roots, we conducted our research on entire plants by evaluating the effect of exogenous MJ on ginsenoside production with the aim of obtaining new approaches to study ginsenoside biosynthesis response to MJ in vivo. Methods: Different parts of MJ-treated ginseng plants were analyzed for ginsenoside contents (fine root, root body, epidermis, rhizome, stem, and leaf) by high-performance liquid chromatography. Results: The total ginsenoside content of the ginseng root significantly increased after 2 d of MJ treatment compared with the control not subjected to MJ. Our results revealed that MJ treatment enhances ginsenoside production not in the epidermis but in the stele of the ginseng root, implying transportation of ginsenosides from the root vasculature to the epidermis. Application of MJ enhanced protopanaxadiol (PPD)-type ginsenosides, whereas chilling treatment induced protopanaxatriol (PPT)-type ginsenosides. Conclusion: These findings indicate that the production of PPD-type and PPT-type ginsenosides is differently affected by abiotic and biotic stresses in the ginseng plant, and they might play different defense mechanism roles.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1057-1063
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• 2011

Herein, a novel ginsenosidase, named ginsenosidase type IV, hydrolyzing 6-O-multi-glycosides of protopanaxatriol-type ginsenosides (PPT), such as Re, R1, Rf, and Rg2, was isolated from the Aspergillus sp. 39g strain, purified, and characterized. Ginsenosidase type IV was able to hydrolyze the 6-O-${\alpha}$-L-($1{\rightarrow}2$)-rhamnoside of Re and the 6-O-${\beta}$-D-($1{\rightarrow}2$)-xyloside of R1 into ginsenoside Rg1. Subsequently, it could hydrolyze the 6-O-${\beta}$-D-glucoside of Rg1 into F1. Similarly, it was able to hydrolyze the 6-O-$_{\alpha}$-L-($1{\rightarrow}2$)-rhamnoside of Rg2 and the 6-O-${\beta}$-D-($1{\rightarrow}2$)-glucoside of Rf into Rh1, and then further hydrolyze Rh1 into its aglycone. However, ginsenosidase type IV could not hydrolyze the 3-O- or 20-O-glycosides of protopanaxadiol-type ginsenosides (PPD), such as Rb1, Rb2, Rb3, Rc, and Rd. These exhibited properties are significantly different from those of glycosidases described in Enzyme Nomenclature by the NC-IUBMB. The optimal temperature and pH for ginsenosidase type IV were $40^{\circ}C$ and 6.0, respectively. The activity of ginsenosidase type IV was slightly improved by the $Mg^{2+}$ ion, and inhibited by $Cu^{2+}$ and $Fe^{2+}$ ions. The molecular mass of the enzyme, based on SDS-PAGE, was noted as being approximately 56 kDa.

• Journal of Ginseng Research
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• 제42권2호
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• pp.123-132
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• 2018

Ginseng has gained its popularity as an adaptogen since ancient days because of its triterpenoid saponins, known as ginsenosides. These triterpenoid saponins are unique and classified as protopanaxatriol and protopanaxadiol saponins based on their glycosylation patterns. They play many protective roles in humans and are under intense research as various groups continue to study their efficacy at the molecular level in various disorders. Ginsenosides Rb1 and Rg1 are the most abundant ginsenosides present in ginseng roots, and they confer the pharmacological properties of the plant, whereas ginsenoside Rg3 is abundantly present in Korean Red Ginseng preparation, which is highly known for its anticancer effects. These ginsenosides have a unique mode of action in modulating various signaling cascades and networks in different tissues. Their effect depends on the bioavailability and the physiological status of the cell. Mostly they amplify the response by stimulating phosphotidylinositol-4,5-bisphosphate 3-kinase/protein kinase B pathway, caspase-3/caspase-9-mediated apoptotic pathway, adenosine monophosphate-activated protein kinase, and nuclear factor kappa-light-chain-enhancer of activated B cells signaling. Furthermore, they trigger receptors such as estrogen receptor, glucocorticoid receptor, and N-methyl-$\text\tiny{D}$-aspartate receptor. This review critically evaluates the signaling pathways attenuated by ginsenosides Rb1, Rg1, and Rg3 in various tissues with emphasis on cancer, diabetes, cardiovascular diseases, and neurodegenerative disorders.

• Journal of Ginseng Research
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• 제46권3호
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• pp.444-453
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• 2022

Background: Compound K (CK) is among the protopanaxadiol (PPD)-type ginsenoside group, which produces multiple pharmacological effects. Herein, we examined the effects of CK on muscle atrophy under hyperlipidemic conditions along with its pro-myogenic effects. Further, the molecular pathways underlying the effects of CK on skeletal muscle have been justified. Methods: C2C12 myotubes were treated with palmitate and CK. C2C12 myoblasts were differentiated using CK for 4-5 days. For the in vivo experiments, CK was administered to mice fed on a high-fat diet for 8 weeks. The protein expression levels were analyzed using western blotting analysis. Target protein suppression was performed using small interfering (si) RNA transfection. Histological examination was performed using Jenner-Giemsa and H&E staining techniques. Results: CK treatment attenuated ER stress markers, such as eIF2a phosphorylation and CHOP expression and impaired myotube formation in palmitate-treated C2C12 myotubes and skeletal muscle of mice fed on HFD. CK treatment augmented AMPK along with autophagy markers in skeletal muscle cells in vitro and in vivo experiments. AMPK siRNA or 3-MA, an autophagy inhibitor, abrogated the impacts of CK in C2C12 myotubes. CK treatment augmented p38 and Akt phosphorylation, leading to an enhancement of C2C12 myogenesis. However, AMPK siRNA abolished the effects of CK in C2C12 myoblasts. Conclusion: These findings denote that CK prevents lipid-induced skeletal muscle apoptosis via AMPK/autophagy-mediated attenuation of ER stress and induction of myoblast differentiation. Therefore, we may suggest the use of CK as a potential therapeutic approach for treating muscle-wasting conditions associated with obesity.

• Journal of Ginseng Research
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• 제47권1호
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• pp.74-80
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• 2023

Background: Although many studies have evaluated the efficacy and pharmacokinetics of Korean Red Ginseng (KRG) components (Rg1, Rb1, Rg3, Rd, etc.), few have examined the in vivo pharmacokinetics of the radiolabeled components. This study investigated the pharmacokinetics of ginsenosides and their metabolite compound K (CK), 20(s)-protopanaxadiol (PPD), and 20(s)-protopanaxatriol (PPT) using radioisotopes in rat oral administration. Methods: Sprague-Dawley rats were dosed orally once with 10 mg/kg of the tritium(3H) radiolabeled samples, and then the blood was collected from the tail vein after 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, 48, 96, and 168 h. Radioactivity in the organs, feces, urine, and carcass was determined using a liquid scintillation counter (LSC) and a bio-imaging analyzer system (BAS). Results and conclusion: After oral administration, as the ³H-labeled ginsenosides were converted to metabolites, C_max and half-life increased, and T_max decreased. Interestingly, Rb1 and CK showed similar values, and after a single oral administration of components, the cumulative excretion ratio of urine and feces was 88.9%-92.4%. Although most KRG components were excreted within 96-168 h of administration, small amounts of components were detected in almost all tissues and mainly distributed to the liver except for the digestive tract when observed through autoradiography. This study demonstrated that KRG components were distributed to various organs in the rats. Further studies could be conducted to prove the bioavailability and transmission of KRG components to confirm the mechanism of KRG efficacy.

• Journal of Ginseng Research
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• 제47권2호
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• pp.183-192
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• 2023

Viral infections are known as one of the major factors causing death. Ginseng is a medicinal plant that demonstrated a wide range of antiviral potential, and saponins are the major bioactive ingredients in the genus Panax with vast therapeutic potential. Studies focusing on the antiviral activity of the genus Panax plant-derived agents (extracts and saponins) and their mechanisms were identified and summarized, including contributions mainly from January 2016 until January 2022. P. ginseng, P. notoginseng, and P. quinquefolius were included in the review as valuable medicinal herbs against infections with 14 types of viruses. Reports from 9 extracts and 12 bioactive saponins were included, with 6 types of protopanaxadiol (PPD) ginsenosides and 6 types of protopanaxatriol (PPT) ginsenosides. The mechanisms mainly involved the inhibition of viral attachment and replication, the modulation of immune response by regulating signaling pathways, including the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway, cystathionine γ-lyase (CSE)/hydrogen sulfide (H₂S) pathway, phosphoinositide-dependent kinase-1 (PDK1)/ protein kinase B (Akt) signaling pathway, c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) pathway, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. This review includes detailed information about the mentioned antiviral effects of the genus Panax extracts and saponins in vitro and in vivo, and in human clinical trials, which provides a scientific basis for ginseng as an adjunctive therapeutic drug or nutraceutical.